Heretofore, each unit cell of a usual fuel cell has had a structure in which separators are provided on both sides of a membrane electrode assembly (hereinafter referred to simply as the “MEA”) having an electrolyte membrane, an anode electrode disposed on one surface of the electrolyte membrane and a cathode electrode disposed on the other surface thereof. Moreover, in the fuel cell, a plurality of unit cells are stacked to obtain a cell stack, and at both ends of the cell stack in a cell stack direction, current collection plates (terminal plates), insulators, pressure plates, end plates and the like are disposed.
Such a fuel cell has a fact that the temperature of the unit cells (hereinafter referred to as “the end cells”) disposed at the ends of the cell stack is lower than that of the other unit cells of the cell stack. This is because the end cells are influenced by heat release from the terminal plates, the insulators, the pressure plates, the end plates and the like, and the temperature of a refrigerant of an end refrigerant passage drops. In particular, it is known that in the end cell disposed at the end of the cell stack on a total minus side thereof, the temperature of an anode side becomes lower than that of a cathode side. This temperature drop might cause the deterioration of the performance of the fuel cell.
In recent years, another fuel cell has been introduced in which an insulating layer (an insulating dummy cell) is disposed on an outer side from a terminal plate of a cell stack in a cell stack direction thereof to suppress heat release from an end cell and to increase a current collection efficiency (see, e.g., Patent Document 1).
Moreover, there has been introduced still another fuel cell comprising a dummy cell disposed corresponding to a power generation cell in at least one end of a cell stack in a cell stack direction thereof, and in at least the dummy cell or between the dummy cells, an insulating space portion is formed, whereby the dummy cell itself functions as an insulating layer (see, e.g., Patent Document 2).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2006-332006
[Patent Document 2] Japanese Patent Application Laid-Open No. 2006-147502